Do experts recommend separate inverters and chargers?

[Kit_L]

I am looking to make a modest upgrade to our vessel's solar system. Presently, we have a tiny panel which trickle charges the two house bank Trojan T105s.
We run the generator for an hour or so in the evening, and load it fully:

AC battery charger (charges house batteries)
Cook dinner, one or two plates
Can run oven and/or microwave, but usually do not
run small electric heater, 1,000W
boil water
heat water via 800W element in a water heater.

The generator is a 6KVa Kohler. We are going to add 4 T105s to the system, making 6 in all.

We intend to add two 400W panels. So, in addition to an MPPT controller, we will need a new charger and an inverter.

Because we really only need a small inverter (to charge two computers, two phones, two tablets), we are thinking that an 800W Victron might do the job. But it's only capable of charging at 35A, so not enough for the 6-battery system. The larger 1,600W inverter–charger would be (charges to 70A).

Would it be better to size the charger to the bank size and use a separate inverter?

So, some questions:


Trojan's site says that these batteries should be charged at 10–13% of the 20-hour capacity rating, so 60–70A for the six, if we go with six, or 40A if we decide only four.

And I have seen advice here that recommends against combination inverter–chargers (like the Victron Multi-Plus units), but I would really like to know what people think the fundamental advantages/disadvantages of separate vs. combined units are, apart from what I have mentioned above. TIA.

 

[psneeld]

Combo chargers/inverters are like combo electronics...divergent opinions with no real reasons to think one is better over the other than I will admit I have always been a little nervous over the AC transfer part reliability. Didn't keep me from installing one though.

I did have a backup battery charger and was very happy that I had it. It was a result of upgrades to the boat and it was a great little charger.

The reason I was happy I had it was because on one trip to the Fl Keys where anchoring out was the only possibility most nights, the battery charger died. At the time, with the separate inverter/charger setup and a dead battery charger, I had very limited (to none) options to charge the batteries. It was too cloudy to charge adequately through my solar. So after that trip and the battery charger replacement and later the addition of the larger (and integrated) charger/inverter, the stand alone charger was peace of mind. It also was handy as it could run at a lower setting off my little 1000 Watt Honda generator sipping gas when all I needed was to charge the batteries.

So bottom line, I have no problems with inverter/chargers...and I am a big proponent of either a backup battery charger or adequate solar in poor conditions if you cruise to where plugging in is not an option.

 

[ranger58sb]

And I have seen advice here that recommends against combination inverter–chargers (like the Victron Multi-Plus units), but I would really like to know what people think the fundamental advantages/disadvantages of separate vs. combined units are, apart from what I have mentioned above. TIA.

NOT an expert...

A pro is a bit of space saved by the combo. Maybe a bit of weight -- probably insignificant? One install cost.

And it might also save a bit of wiring run complexity. (Not the actual connections; I mean getting wire from here to there.)

One con is that you lose both functions if one craps out.

I decided in favor of the combo, recognizing it'll hurt a bit more -- in unit cost, maybe not so much labor cost -- if one or the other function goes south. And taking into account that we're generally flexible with boating time, not living aboard, etc... so if we're down, awaiting repairs, mostly that's something we can work around.

We haven't had any issues with automatic transfer. Had a ProMariner combi on the last boat, recently installed a Victron MultiPlus on this one.

-Chris

 

[ksanders]

Pretty much every major brand of inverters/chargers are selling a single unit that does both functions.

Your choices in a separate high capacity charger and inverter are extremely limited.

 

[Tom.B]

In the past, I was a huge proponent of separate devices, however, when it came to an actual install, I went with a Victron inverter charger. There was some concern, but the technology that used to mean Jack of all trades- master on none has pretty much been worked out. The two systems work together so closely anyway, it really seems smarter to have it this way now. And like was said above, it is getting harder to even find sizable units that are not combos anymore.

 

[twistedtree]

I wouldn't hesitate for a second over a combo unit. But the comment about redundancy is a good one, so perhaps consider leaving your existing charger in place as a backup, and as a way to recharge a little faster if you choose.

 

[JDCAVE]

We have a Magnum MS-2812 and have found it reliable. Now, we leave the inverter switched to “off” unless required or we are travelling. We are principally a DC boat using up to 250 amps per day at 12 VDC. 1125 amp hours with 10 T-105’s. And these are on their 9th season. We also have solar panels and a Northern Lights Genny. There’s quite a bit of redundancy. The Genny, main engine and Thruster batteries are all on separate chargers.

We will change out the T-105’s in the off-season, possibly switching over to 4-500 amp hours of LFP.

Jim

 

[OldDan1943]

I have a Xantex 40 Amp True Charger
and a 1800 watt inverter. I have a preference for separate units, in case on goes belly up.
I have 2 additional small inverters to support 2 TVs
It may not be the greatest system but it seem to work.
I should add, I have 4x4D batteries. One for start, 3 for house.

 

[ranger58sb]

One con is that you lose both functions if one craps out.

It occurs to me I don't actually know the charger part stops working if the inverter part craps out.

-Chris

 

[tiltrider1]

I haven’t researched this topic lately. My experience has been that the top line charger/inverter is superior to the best stand alone charger coupled to the best stand alone inverter. My Magnum MSH3012 puts out 150 amps of charging while all the stand alone units maxed out at 125 amps. I also get 3000 watts off the inverter were the stand alone maxs out at 2500 watts.

 

[Hippocampus]

Currently facing my inverter/charger has crapped out. Prior owner replaced the original inverter 2 years ago (had a fire) with a 3000 mastervolt . AC panel and wiring has three bus bars. Two work and one doesn’t. Had a electrician on the boat this morning to diagnose. Tells me although my charger works (batteries voltages are fine ) the what’s on the other two bus bars( refrigeration, AC, everything else on the other two bus bars and breakers) the AC outlets are dead. Everything on the DC panel works.
He says the AC to the two working bus bars comes directly from shore power not going through the inverter but the AC to the one dead busbar goes through the inverter. Why? He offered no reason other than perhaps due to load capacity of inverter and to keep key functions working if inverter failed. Of note no change in the situation if on genset or shore power. Genset is AC output.
The boat two away from me but on the same side fried the ends of his 50a cord. Both failures the same day. Tech is saying unrelated. I’m having trouble buying that. Seems too unlikely. I’m also using 50 a but splitting it to two 30s. We checked my cords. No heat or other damage. Get normal AC voltage up to the inverter charger but nothing out of it and none of its lights are on. Don’t know about my next door neighbor. He’s not on his boat.
Questions
Would a surge on the shore power do this?
Why would a inverter/charger fail twice with in 2 years?
Thanks for any thoughts.

 

[ksanders]

Currently facing my inverter/charger has crapped out. Prior owner replaced the original inverter 2 years ago (had a fire) with a 3000 mastervolt . AC panel and wiring has three bus bars. Two work and one doesn’t. Had a electrician on the boat this morning to diagnose. Tells me although my charger works (batteries voltages are fine ) the what’s on the other two bus bars( refrigeration, AC, everything else on the other two bus bars and breakers) the AC outlets are dead. Everything on the DC panel works.
He says the AC to the two working bus bars comes directly from shore power not going through the inverter but the AC to the one dead busbar goes through the inverter. Why? He offered no reason other than perhaps due to load capacity of inverter and to keep key functions working if inverter failed. Of note no change in the situation if on genset or shore power. Genset is AC output.
The boat two away from me but on the same side fried the ends of his 50a cord. Both failures the same day. Tech is saying unrelated. I’m having trouble buying that. Seems too unlikely. I’m also using 50 a but splitting it to two 30s. We checked my cords. No heat or other damage. Get normal AC voltage up to the inverter charger but nothing out of it and none of its lights are on. Don’t know about my next door neighbor. He’s not on his boat.
Questions
Would a surge on the shore power do this?
Why would a inverter/charger fail twice with in 2 years?
Thanks for any thoughts.

Your installation seems pretty normal. For example I have three panels on my boat. Two of the panels are from shorerpower or generator power. The 3rd panel is from the inverter.

Yes a surge could fry equipment, happens all the time.
No clue why two inverters would fail in a couple of years. Many causes or no cause, impossible to speculate.

 

[psneeld]

I set my panels up for 2 busses were direct to shore power and one buss fed the inverter which fed the 3rd buss that fed all the ships outlets except a couple reserved for things like space heaters, other high draw items.

Many inverters use a pass through relay that when not "inverting" or when fed shore power and "charging" are also passing though current to the AC buss they usually feed when inverting.

Agree with Kevin with surges and the near impossibility of narrowing down a failure without tearing into the equipment.

 

[twistedtree]

With initial adoption of inverters in boats, people only connected select loads to the inverter. This was motivated by lower power inverters, so only loads that had to be on the inverter, were on the inverter. And the inverter was only turned on when needed.


Over time people got used to the convenience of always having AC power, so the inverters got left on more of the time, if not all of the time. And more and more loads got moved to the inverters.


Now many boats are being built with nearly all loads on inverters, only leaving off those that make no sense to have on the inverter, like extra shore chargers.


I think your 3 AC buses are reflective of this evolution. Sounds like it's time for a new inverter, and I would not get another Mastervolt. They are fine when they work, but in my experience if you have any issues or questions, nobody is home... Victron seems to be best, or perhaps more accurately, the least bad.

 

[Insequent]

There is one big advantage of having seperate inverters and chargers, but only likely to apply to a small number of boats.

The combo units are usually (always?) set for either Euro or Nth American voltage and frequency, and cannot be reconfigured by the user. Whereas the seperate chargers, from Victron at least, have the capacity to accept both 120 & 240 volts and both 60 Hz & 50 Hz and they select automatically. Obviously only one V/Hz pairing at a time.

So if your boat needs the flexibility to handle both as you cruise around the place then seperate chargers simplify shore power hook-ups. Not many will do this.

For my own boat, purchased in the USA and operated there for a year I installed a combo, a Quattro 240V 50Hz unit as I had some appliances with that AC spec. Initially I was also running some 120V appliances so I had a step-down transformer as well. Those appliances were getting 50 Hz AC though. For the resistive load appliances that was fine. For the inductive load types, some are still working but others were replaced over time when I brought the boat back to Australia (240V/50 Hz power). In order to have battery charging capacity before leaving USA I also had a Victron 70A charger which is multi voltage and frequency. In conjunction with 1800W of solar (at the time) I was fine at marina's.

 

[Kit_L]

@Insequent: I understand your use pattern perfectly. Ours will be different, in that we will not need to access 60Hz or 120V power, or make it. I will have to look up the meanings of resistive and inductive loads!

I do intend to bring our vessel to Manly, Qld at some point mid next year (the best electricians I have ever worked with work out of Manly).

 

[Flatswing]

It occurs to me I don't actually know the charger part stops working if the inverter part craps out.

-Chris

My Magnum 2812 crapped out on the penultimate day of our Bahamas cruise. The inverter wouldn’t but the 125A charger is fine and the pass through(stand by mode) is still working fine so at least I could run all my 120v appliances including fridge off the generator or shore power. My understanding is that most inverter chargers are designed to fail in pass through/stand by mode.

I also have a 60A 3 channel charger as back up in addition to a small 220W solar panel & 30A Mppt Controller.

 

[ranger58sb]

My Magnum 2812 crapped out on the penultimate day of our Bahamas cruise. The inverter wouldn’t but the 125A charger is fine and the pass through(stand by mode) is still working fine so at least I could run all my 120v appliances including fridge off the generator or shore power. My understanding is that most inverter chargers are designed to fail in pass through/stand by mode.

That's useful, thanks.

-Chris

 

[Simi 60]

I do intend to bring our vessel to Manly, Qld at some point mid next year (the best electricians I have ever worked with work out of Manly).

Who would that be?
Some of the worst ones I have ever used come from there as well.

 

[OldDan1943]

Your boat's electrical system is a balancing act. First, you have to have the batteries to support the inverter. Then you need, in my mind, 2 ways to charge the batteries when away from the dock.

 

[Kit_L]

@OldDan: that's sound thinking—there's never a reason to not have redundancy. Re. the charger, I have a big CTEC smart charger at home that I will bring aboard; in an emergency with boat charger out, I'd run the generator and use the CTEC to charge the batteries.

 

[RobbGrrr]

I'm a big fan of the Victron charger/inverter I've got onboard. Mostly because I have just a 30A shore connection.

The unit will modulate the charge current to the batteries down from the 100A max I've set based on what the rest of the boat is consuming. This keeps the boat from exceed my available 30A shore supply.

I think the integration is invaluable.

 

[bkcorwin]

One thing to be aware of with Victron, is that as far as I can tell and have experienced, there is ZERO technical support available directly from Victron. Their tech support website reads

"For technical assistance, please follow the steps below to quickly identify the issue. Feel free to contact the dealer you bought the product from, they are happy to help, trained with the highest of know-how and are responsible to assist you."

This is useless in a lot of situations. EG, you bought the product from amazon. OR also, i've found some vendors aren't able to provide much support. I had a technical question and was just directed by my vendor to go ask on the Victron Community Forum. I did and haven't heard anything from there either.

Not to say I don't like the products, my boat is heavily victron based, dual skylla chargers, dual quattros, cerbos, bmvs, phoenix inverters. So the stuff seems to work OK, but damned if I can find someone to ask a question of.

 

[MOJO]

Have always used inverter/charger combo and been very happy with them. The combo units seem to have a larger charger than you can find as a stand-alone unit. Also, don't skimp on the inverter, even if you think you only need it for cell phone & computer... it's nice to be able to plug in 110v power tools, fans, transfer pumps, etc.

 

[OldDan1943]

Have always used inverter/charger combo and been very happy with them. The combo units seem to have a larger charger than you can find as a stand-alone unit. Also, don't skimp on the inverter, even if you think you only need it for cell phone & computer... it's nice to be able to plug in 110v power tools, fans, transfer pumps, etc.

and remember, you must have the batteries to support your inverter.

 

[Phyrcooler]

Having had a Magnum Inverter Charger that had “issues”… I became a proponent of separating. Nothing like showing up on a Friday evening for a long holiday weekend to find an error code flashing, your house bank flat, and no way to recharge other than a very long run of the engines. No voltage was being passed through either. Thus began a long journey to sort out the unit and many stressful days on the boat. In the middle of this saga, I had my electrician install a large rotary bi-pass switch that allowed the shore power circuit to bi-pass the inverter completely. This was a smart move, because at least we had things like the A/C and microwave that the family deemed essential at the dock for all those times we showed up and the Magnum had gone into fault mode again!

Currently we’ve returned to sailing, and function just fine without an inverter. If I ever return to trawler life, my preference would be to separate. But if combined I would absolutely install a bi-pass for the AC power as well as a backup charger. If I ever add an inverter to the sailboat, it will be a small standalone pure sine wave.

 

[old-School]

Outback Inverter/Charger

I finally ended my electrical woes two years ago, I had a completely new system installed.
Check it out. I just know it works on a GB 42 Classic. Good luck. I spent many bucks to get to a system that works.

 

[Helmsman]

I finally ended my electrical woes two years ago, I had a completely new system installed.
Check it out. I just know it works on a GB 42 Classic. Good luck. I spent many bucks to get to a system that works.

What did you get? I don’t see an attachment.

 

[sunchaser]

I'm a big fan of the Victron charger/inverter I've got onboard. Mostly because I have just a 30A shore connection.

The unit will modulate the charge current to the batteries down from the 100A max I've set based on what the rest of the boat is consuming. This keeps the boat from exceed my available 30A shore supply.

I think the integration is invaluable.

Modulation is not unique to Victron. If one is inverter/charger shopping insure your new unit has this feature especially for times when tied to 30 amp pedestals.